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Intra and Inter-Spore Variability in Rhizophagus irregularis AOX Gene.

Campos C, Cardoso H, Nogales A, Svensson J, Lopez-Ráez JA, Pozo MJ, Nobre T, Schneider C, Arnholdt-Schmitt B - PLoS ONE (2015)

Bottom Line: Nevertheless, virtually nothing is known on the involvement of AMF AOX on symbiosis establishment, as well on the existence of AOX variability that could affect AMF effectiveness and consequently plant performance.The analysis of RiAOX polymorphisms in single spores of three different isolates showed a reduced variability in one spore relatively to a group of spores.A high number of polymorphisms occurred in introns; nevertheless, some putative amino acid changes resulting from non-synonymous variants were found, offering a basis for selective pressure to occur within the populations.

View Article: PubMed Central - PubMed

Affiliation: EU Marie Curie Chair, ICAAM-Instituto de Ciências Agrárias e Ambientais Mediterrânicas, IIFA-Instituto de Formação e Investigação Avançada, Universidade de Évora, Núcleo da Mitra, Évora, Portugal.

ABSTRACT
Arbuscular mycorrhizal fungi (AMF) are root-inhabiting fungi that form mutualistic symbioses with their host plants. AMF symbiosis improves nutrient uptake and buffers the plant against a diversity of stresses. Rhizophagus irregularis is one of the most widespread AMF species in the world, and its application in agricultural systems for yield improvement has increased over the last years. Still, from the inoculum production perspective, a lack of consistency of inoculum quality is referred to, which partially may be due to a high genetic variability of the fungus. The alternative oxidase (AOX) is an enzyme of the alternative respiratory chain already described in different taxa, including various fungi, which decreases the damage caused by oxidative stress. Nevertheless, virtually nothing is known on the involvement of AMF AOX on symbiosis establishment, as well on the existence of AOX variability that could affect AMF effectiveness and consequently plant performance. Here, we report the isolation and characterisation of the AOX gene of R. irregularis (RiAOX), and show that it is highly expressed during early phases of the symbiosis with plant roots. Phylogenetic analysis clustered RiAOX sequence with ancient fungi, and multiple sequence alignment revealed the lack of several regulatory motifs which are present in plant AOX. The analysis of RiAOX polymorphisms in single spores of three different isolates showed a reduced variability in one spore relatively to a group of spores. A high number of polymorphisms occurred in introns; nevertheless, some putative amino acid changes resulting from non-synonymous variants were found, offering a basis for selective pressure to occur within the populations. Given the AOX relatedness with stress responses, differences in gene variants amongst R. irregularis isolates are likely to be related with its origin and environmental constraints and might have a potential impact on inoculum production.

No MeSH data available.


Related in: MedlinePlus

Frequency of SNVs along the RiAOX sequence on the INOQ, BEG144 and BEG72 isolates.
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pone.0142339.g007: Frequency of SNVs along the RiAOX sequence on the INOQ, BEG144 and BEG72 isolates.

Mentions: The frequency (read count divided by read coverage) distribution of all variants (in relation to the total number of variants in one spore) was plotted on histograms, ranging from rare (<2% of frequency of occurrence) until variants that showed a frequency of occurrence of almost 100% (Fig 6). All isolates presented highly frequent polymorphisms (>80–100% of frequency of occurrence), particularly SNVs (Fig 6). Nevertheless, most of variants showed until 20% of frequency of occurrence. The frequency of SNVs was relatively similar amongst isolates, ranging from low frequency SNVs until highly frequent SNVs, with several of them showing frequencies close to 100% (Fig 7A–7C).


Intra and Inter-Spore Variability in Rhizophagus irregularis AOX Gene.

Campos C, Cardoso H, Nogales A, Svensson J, Lopez-Ráez JA, Pozo MJ, Nobre T, Schneider C, Arnholdt-Schmitt B - PLoS ONE (2015)

Frequency of SNVs along the RiAOX sequence on the INOQ, BEG144 and BEG72 isolates.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4634980&req=5

pone.0142339.g007: Frequency of SNVs along the RiAOX sequence on the INOQ, BEG144 and BEG72 isolates.
Mentions: The frequency (read count divided by read coverage) distribution of all variants (in relation to the total number of variants in one spore) was plotted on histograms, ranging from rare (<2% of frequency of occurrence) until variants that showed a frequency of occurrence of almost 100% (Fig 6). All isolates presented highly frequent polymorphisms (>80–100% of frequency of occurrence), particularly SNVs (Fig 6). Nevertheless, most of variants showed until 20% of frequency of occurrence. The frequency of SNVs was relatively similar amongst isolates, ranging from low frequency SNVs until highly frequent SNVs, with several of them showing frequencies close to 100% (Fig 7A–7C).

Bottom Line: Nevertheless, virtually nothing is known on the involvement of AMF AOX on symbiosis establishment, as well on the existence of AOX variability that could affect AMF effectiveness and consequently plant performance.The analysis of RiAOX polymorphisms in single spores of three different isolates showed a reduced variability in one spore relatively to a group of spores.A high number of polymorphisms occurred in introns; nevertheless, some putative amino acid changes resulting from non-synonymous variants were found, offering a basis for selective pressure to occur within the populations.

View Article: PubMed Central - PubMed

Affiliation: EU Marie Curie Chair, ICAAM-Instituto de Ciências Agrárias e Ambientais Mediterrânicas, IIFA-Instituto de Formação e Investigação Avançada, Universidade de Évora, Núcleo da Mitra, Évora, Portugal.

ABSTRACT
Arbuscular mycorrhizal fungi (AMF) are root-inhabiting fungi that form mutualistic symbioses with their host plants. AMF symbiosis improves nutrient uptake and buffers the plant against a diversity of stresses. Rhizophagus irregularis is one of the most widespread AMF species in the world, and its application in agricultural systems for yield improvement has increased over the last years. Still, from the inoculum production perspective, a lack of consistency of inoculum quality is referred to, which partially may be due to a high genetic variability of the fungus. The alternative oxidase (AOX) is an enzyme of the alternative respiratory chain already described in different taxa, including various fungi, which decreases the damage caused by oxidative stress. Nevertheless, virtually nothing is known on the involvement of AMF AOX on symbiosis establishment, as well on the existence of AOX variability that could affect AMF effectiveness and consequently plant performance. Here, we report the isolation and characterisation of the AOX gene of R. irregularis (RiAOX), and show that it is highly expressed during early phases of the symbiosis with plant roots. Phylogenetic analysis clustered RiAOX sequence with ancient fungi, and multiple sequence alignment revealed the lack of several regulatory motifs which are present in plant AOX. The analysis of RiAOX polymorphisms in single spores of three different isolates showed a reduced variability in one spore relatively to a group of spores. A high number of polymorphisms occurred in introns; nevertheless, some putative amino acid changes resulting from non-synonymous variants were found, offering a basis for selective pressure to occur within the populations. Given the AOX relatedness with stress responses, differences in gene variants amongst R. irregularis isolates are likely to be related with its origin and environmental constraints and might have a potential impact on inoculum production.

No MeSH data available.


Related in: MedlinePlus